Yes, a company can buy and sell derivatives securities without registering itself as an NBFC. The NBFC (Non-banking Financial Cooperation) is an entity involved under the principal business of acquisition of shares/bonds, advancing loans, insurance business, trading in marketable securities, etc. If any company is not registered as NBFC under Companies Act, 2013, that means their principal business involves agriculture, industrial activity, trading of products (other than securities), providing services, or property dealing.